Polyimide resins are insoluble, infusible, ultra-heat resistant resins that have superior properties such as thermal oxidation resistance, heat resistance, radiation resistance, low-temperature resistance and chemical resistance. Consequently, polyimide resins are used in a wide range of fields, including electronic materials.
Application examples of polyimide resins in the field of electronic materials include insulating coating materials, insulating films, semiconductors and electrode protective films of TFT-LCD. Recently, the use of polyimide resin is being considered for use as a flexible substrate utilizing the flexibility thereof that is capable of serving as an alternative to glass substrates conventionally used in the field of display materials. Patent Document 1, for example, discloses a polyimide resin composition having little variations in film thickness along with a flexible display substrate that uses this polyimide resin composition.
In fields requiring transparency, polyimide resins have been proposed that demonstrate transparency by inhibiting the formation of charge transfer complexes by means such as introducing fluorine atoms into the resin backbone, imparting flexibility to the resin backbone or introducing bulky side chains. Patent Document 2, for example, proposes the use of a polyimide resin introduced with 2,2′-bis(trifluoromethyl)benzidine (to be referred to as “TFMB”) as constituent material of a display device.